Method of and machine for reproducing pattern contours



Oct. 12, 1943. I A. A. MEYER 2,331,337

METHOD OF AND MACHINE FOR REPRODUCING PATTERN CONTOURS Filed May 5, 19397 Sheets-Sheet l J6, NVBNTOQ/ 20 9 C4r/hw' C4. Wager TTO Eys Oct. 12,1943. A. A. MEYER 2,331,337

METHOD OF AND MACHINE FOR REPRODUCING PATTERN CONTOURS Filed May 5, 19397 Sheets-Sheet 3 7 x v 74 92 7 79 7 94 7 a9 Q0 1 ha 73 a 65 t J .fi 7%22 ,1 1" 1 I 1:97 ;6a' Vl-:

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METHOD OF AND MACHINE FOR REPRODUCING PATTERN CONTOURS Filed May 5, 19397 Sheets-Sheet 4 TO HEAD END OF T3 200 END or To HEAD END OF NS s mUW/hur 64. Qf/egen r4 Pm ch14, m

(flTm Eys 1943. A. AQMEYER 2,331,337

METHOD OF AND MACHINE FOR REPRODUCING PATTERN COIQTOURS Filed May 5,1959 7 Sheets-Sheet 5 Mr/hur 04. 07/25 22? Oct. 12, 1943.

A. A. MEYER METHOD OF AND MACHINE FOR REPRODUCING PATTERN CONTOURS FiledMay 5, 1939 7 Sheets-Sheet 6 MH /MU 6% We en 3 F CUM, Pi 1W OQTTOVQIEXSOct.- 12, .1943. A. MEYER 2,331,337

METHOD OF AND MACHINE FOR REPRODUCING PATTERN CONTOURS Filed May 5, 19397 Sheets-Sheet 7 z zzzwm Wr TTO 4 2.7 5

Patented Oct. 12, 1943 METHOD OF AND MACHINE FOR REPRODUCING PATTERNCONTOURS.

Arthur A. Meyer, South Beloit, 111. Application May 5, 1939, Serial No.271,868

28 Claims.

This invention relates to a system of control for causing a controlledobject to traverse a path corresponding to a pattern outline and hasmore particular reference to the reproduction of pattern contours bygoverning the relative movements between a work piece and a tool such asa milling cutter, a cutting torch, a polishing or abrasive Wheel, etc.

One object is to provide a novel method of and machine of the abovegeneral character by which a single tracer element will follow theentire periphery of a pattern automatically without the necessity ofchanging quadrants or otherwise adjusting the control mechanism.

A more detailed object is to govern the relative movements of acontrolled object, such as a cutter, in accordance with the meanposition of a tracer element which is oscillated back and forthlaterally of a pattern outline in directions which are variedautomatically with changes in the pattern contour.

Another object is to provide a novel electrical system controlled by atracer for detecting changes in a pattern contour and to utilize thissystem in a novel way to control an hydraulic operator which is moved inany one or a combination of four rectangular directions.

Still another object is to provide a novel control system for enablingthe movements of a controlled object to reproduce the outline of apattern in the form of a line inscribed on a transparent medium.

A further object is to utilize a photosensitive cell in a novel way tocarry out the foregoing object.

Another object is to provide a novel circuit arrangement for obtainingoptimum sensitivity of the electric system controlled by thephotosensitive cell.

The invention also resides in the novel manner of varying the directionof oscillation of the tracer element relative to the pattern and in thenovel valve arrangement by which precision of control is obtained.

Another object is to provide a control of the above character forreproducing contours incorporating means for selectively adjusting thesize of the reproduced path relative to the size of the pattern outline.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which Figure 1 is a fragmentary perspectiveview of a machine for practicing the present. invention.

Fig. 2 is a plan view of a pattern. Fig. 3 is an hydraulic circuitdiagram.

Fig. 4 is a fragmentary plan sectional view Fig. 8 is a fragmentarysectional view taken along the broken line 8-8 of Fig. 7.

Fig. 9 is an enlarged fragmentary sectional view taken along the line9-9 of Fig. 7.

Fig. 10 is a section taken along the line l0-l0 of Fig. 7.

Figs. 11, 12, and 13 are sectional views taken along the line ll-l l ofFig. 6 and illustrating diflerent valve positions.

Fig. 14 is a sectional view taken along the line I4|4 of Fig. 13.

Fig. 15 shows graphically the manner of proportioning the fiuid flow tothe different hydraulic cylinders.

Figs. 16 to 23 are schematic views showing different positions of thevalve and tracer for causing movement of the controlled object indifferent directions.

Figs. 24, 25,- and 26 are similar views showing different relations ofthe tracer and valve controller for different applications of thecontrol.

Fig. 27 is a schematic view illustrating the progress of the traceraround a pattern.

Fig. 28 is a wiring diagram.

While the invention is susceptible of various modifications andalternative constructions and may be practiced in various ways. I haveillustrated in the drawings and will herein describe the preferredembodiments and manner of carrying out the invention. It is to beunderstood that I do not thereby intend to limit the invention by suchdisclosure but aim to cover all m0difications, alternativeconstructions, methods, and uses falling within the spirit and scope ofthe invention as expressed in the appended claims.

Generally stated, the improved method of controlling the relativemovements of a controlled object in accordance with a pattern contourcomprises oscillating a tracer element back and forth transversely of apattern outline while relatively moving the element along such outline,changing the angles and relative lengths of the oscillations inaccordance with changes in the pattern contour so as to maintain asubstantially constant relationship between-the direction of oscillationand the instantaneous curvature of the outline, and relatively movingthe controlled object along a path corresponding to the mean pathdescribed by said element. The tracer element moves in a small orbitalpath and the angle of oscillation is varied by changing the portion ofthe path through which the element oscillates automatically inaccordance with changes in the direction of motion of the controlledobject so that the entire periphery of the pattern will be tracedwithout the necessity of manual adjustment to change quadrants. Thisenables a single tracer element and controls permanently associatedtherewith to'produce movement of the controlled object in all directionsin a given plane. I

For purposes of illustrating the invention, the object to be controlledis shown as a metal cutting tool in the form of an oxy-acetylene torch Iof Well known construction arranged to direct a cutting flame toward ametal work piece W to cut the latter and reproduce thereon the contourof a pattern 2 (Fig. 2) coacting with the tracer element which, in thepresent instance, comprises a light beam 3 (Fig. '7) emanating from acasing 1. Preferably, the pattern is simply the inner or outer peripheryof an ink or pencil line inscribed on a transparent medium such as asheet 3 of tracing cloth or paper. Depending on the position of thetracer relative to the pattern, the O beam 3 or a predetermined partthereof will or will not be intercepted by the line 2, and the resultingfull-light and reduced light conditions are detected by a lightsensitive device 5 and utilized to control a power actuating mechanismby which the controlled object or tool is moved relative to the workpiece and the in unison along the pattern outline.

Herein, the pattern carrier 4 is mounted on a transparent plate 6 ofglass or the like removably supported at its side edges in a stationaryframe 8. The cutter I, in proper operative position relative to thework, is mounted on a carriage 9 which is slidable in ways II on asaddle Ill. The latter and a lateral extension I2 thereof are slidablealong ways I3 extending at right angles to the ways II and formed on asuitable base I4.

Feeding of the saddle along the ways I3 and cross feeding of thecarriage 9 is accomplished by power actuated means which is relativelysluggish in response to its control so that the carriage does notrespond to a measurable degree to the individual oscillations of thetracer. In the present instance, this means comprises two hydraulicactuators having cylinders I5 and I5 respectively secured to the saddleI0 and bed I4 and coacting with pistons I1 and I8 the rods I9 and 29 ofwhich are anchored to the carriag .9 and to the saddle I0.

By supplying pressure fluid through conduits 23 and 24 to the rod andhead ends of the cylinder I6, the saddle I0 supportingthe carriag 9 willbe moved relative to the bed in opposite directions which, for theconvenience of descrip tion, will be referred to as north and southrespectively. Similarly, by introducing fluid through conduits 2| and 22to the head and rod ends of the cylinder I5, the carriage 9 may be movedin opposite directions, indicated as east and west, along theperpendicular path defined by the ways II. By admitting fluidsimultaneously to one end of one cylinder and one end of the othercylinder, and by accurately metering the relative rates of such flow tothe respective ends, it will be apparent that the carriage and tracermounting is fed withdraw oil from a sump saddle may be moved so as toproduce a resultant motion of the cutter. and tracer in any NW, SW, NE,or SE direction, that is, at any angle within a complete circle.

Fluid such as oil is placed under pressure by a gear pump 25 driven byan electric motor 26 to 21 and deliver the same to a conduit 28.Regulation of the volume of fluid delivered to one or both of thecylinders to vary the rate of feed of the carriage 9 may be efiected bymanual adjustment of a valve 29 through which any selected part of thepump output may be by-passed to the return line 30. In the presentinstance, the pump 25 and the motor 26 are mounted on the carriage andthe conduits 2I, 22, 23 and 24 are flexible in part to permit movementof the carriage relative to the saddle.

While a single valve unit may be employed for selectively controllingand metering the fluid flow to the cylinder ends, this is accomplishedherein by two separated valves 3| and 32 mounted on the carriage 9 andrespectively controlling the flow to opposite ends of the east-westcylinder I 5 and the north-south cylinder I6. The valve 32 (see Figs. 6and 11 to 16) comprises a casing 33 having angularly spaced and 36extending through its side wall and respectively communicating throughsuitable fittings with the conduits 23, 24, and the supply line 28. Thepassages terminate in the wall of a cylinder 31 in the casing. A passage38 leading from a branch 39 of the returnline 30 terminates in a port inthe bottom of the casing 33 midway between the passages 34 and 35.

The movable member of the valve 32 is a cylindrical rotor 40 journaledin the cylinder 31 and rigid with a shaft M which projects upwardlythrough a plug 42 closing the upper end of the casing 33 and carries anarm 41. The rotor is shorter than the cylinder 31 and does not cover thesupply passage 36 so that a chamber 43 above the rotor is always underpressure. Passages 44 and 45 in the rotor open upwardly and alsoradially so as to connect the pressure chamber 43 with the passages 34and 35 in different half portions of the rotor movement. The rotor iscut out to form a segmental recess 46 which is in constant communicationwith the drain outlet 38 and is adapted to register with one or theother of the passages 34 and 35. The arm 41 and the valve member 40oscillat through angles 12. and s. With the arm positioned as shown inFigs. 11 and 16, the passages 34 and 44 are in full register and thepassage 35 is connected to the drain through the recess 46. Fluid flowsat a maximum rate from the supply line 28 to the rod end of the cylinderI6 and to 'the drain from the head end resulting in a maximum rate oftravel of the saddle I2 in the north direction. As the arm 41 is swungclockwise through the angle n, the flow is decreased progressively toreduce correspondingly the rate or feed in the north direction. The flowis cut of! completely when the arm 41 is in the mid-position shown inFigs. 12 and 18, both ports 34 and 35 then being covered by the rotor49. In continued clockwise turning of the arm through the angle s, thepassage 45 is brought into register with passage 35, fluid being therebyadmitted to the head end of the cylinder I6 and drained from the rodend, thereby initiating movement of the saddle III in the southdirection. This feed rate is increased progressively in the continuedturning of the arm through the angle passages or bores 34, 35,

s, being a maximum when the rotor is positioned as shown in Figs. 13 and20.

The valve 3| is of the same construction as the valve 32 and forconvenience the corresponding parts have been indicated by the same butprimed reference numerals. The arm 41' is movable through angles e tomodulate the flow of fluid through the passages 44' and 34' (Fig. 16) tothe head end of the cylinder l and permit the draining of the rod endthrough the passages 35', the recess 46, and the passage 38'. In theextreme east position (Fig. 18), the passages 34' and f are in fullregister while in the mid-position of the arm 41' (Fig. 16), thepassages 34' and 35' are covered by the rotor and no fluid flows eitherto or from the cylinder l5. As the arm moves through the angle w, thefluid is permitted to flow to the rod end of the cylinder l5 through theregistering passages 35' and 45', a maximum flow occurring in theextreme west position (Fig. 22).

Provision is made for actuating the two valves 3| and 32 from a commonmember which assumes different positions corresponding to theinstantaneous contour of the pattern being traced and accuratelypositions the two valves to produce a resultant motion of the cuttercorresponding tosuch contour. Preferably, the valve actuator is a rotarymember and, as shown here in, takes the form of a disk fast on the upperend of a vertical shaft 5| journaled in the forward end of the carriage9. Fast on the shaft beneath the disk is an eccentric cam 52 acting onfollower rings 53 and 54 respectively rigid with arms 55 and 55 the freeends of which are pivotally connected at 5'! and 58 to the free ends ofthe arms 41 and 41'.

Since the eccentric 52 is common to both of the followers, the arms 41and 41' are arranged so that lines through the pivots 57 and 58 and theeccentric axis will be disposed at right angles to each other as shownin Fig. 16. Also, the throw of the eccentric and the lengths of the armsare such that when the arm 41 is in its opposite limit positions N or S(Figs. 16 and 20), the arm 41' is in its mid-position in which no fluidis flowing to the cylinder l5. Likewise, in the extreme E and Wpositions of the arm 41' (Figs. 18 and 22) the arm 41 will be in its midor neutral position. Fig. 15 shows graphically the manner in which theeffective volume of oil supplied to the line 28 is proportioned betweenthe two cylinders l5 and I6 for all angular positions of the referencearrow on the valve actuating member 50. For example, in the N positionof the member, all of the fluid flows to the rod end of the NS cylinderwhich causes the saddle H] to move in the north direc tion. As themember moves toward the Wposition, the flow to the cylinder I6 isdecreased and that to the rod end of the WE cylinder is increasedprogressively causing the carriage and saddle to move simultaneously andproduce a resultant northwest movement corresponding to the position ofthe member. From Fig. 15 and the diagrammatic views Figs. 16 to 23, itwill be apparent that the described valve actuator provices forselective and simultaneous positioning of the valves 3| and 32 toproduce a resultant movement of the cutter in any direction away fromthe point of intersection of the NS and EW axes, the rate of feed of thecutter being determir. :d by the setting of the by-pass valve 29.

cause the angle of oscillation of the tracer r light beam 3 to changeautomatically as set forth above, provision is made formoving the tracerin a small orbital path, preferably circu lar, relative to its mountingon the controlled object and in unison with changes in the position ofthe valve actuating member 50. For this purpose, the conical casing I bywhich the beam is defined is, in the present instance, attached at oneside to an arm 60 (Figs. 7 and 8) the other end of which is fastened toa bar 6! pivotally supported at opposite ends by links 62 constitutingone parallel motion device. The other ends of the links are pivotallysupported on the short leg of an L-shaped piece 64 the long leg of whichis supported by links 63 pivotally supported on the carriageS. The bar6| has a bore 65 receiving a pin 66 which projects eccentrically from ashaft 61 fastened to the lower end of the shaft 5| 'as by a set screw68. By loosening the screw, the

collar 61 may be removed and replaced by a collar having a pin 68 ofdifferent eccentricity or a given collar may be adjusted angularly tovary the angular position of the eccentric axis 69 relative to theposition of the valve actuating member 50. With the casing 1 mounted asabove described by the two parallel motion linkages, it will be apparentthat the light beam 3 will follow the movements of the eccentric axis65, describing a complete circle 10 (Fig. 16) about an axis 10 as thevalve actuating member 50 turns through a complete revolution.

The tracer element or light beam is sharply defined by a suitable systemof lenses TI and 12 for converging the rays of light from a source suchas an electric lamp 13 which may be energized from a secondary I02 of amultiple voltage transformer I03 (Fig. 28). To lighten the parts whichmove with the beam and therefor increase the speed of oscillation of thebeam, the lamp is preferably mounted in a tubular casing 14 clamped by astrap 15 against the front of the carriage 9 in substantial axialalinement with the upper open end of the conical casing 1. Part of thelenses are placed in the tube 14. The casing l is thus adapted tooscillate independently of the light source. The side wall 98 (Fig. 9)which defines the hole 99 through which the beam 3 is directed from thecasing I is preferably cut back as shown in Fig. 9 to provide a sharplydefined beam. The same result may be obtained by making the end of thecasing I extremely thin walled.

Various power actuated mechanisms may be employed to effect oscillationof the valve actuating member 50 back and forth in response to fulllight and no light conditions detected by the tracer. This isaccomplished herein by selective energization of a reversible electricmotor driving means herein shown as comprising two electromagneticclutches I04 and I05 for connecting the member 50 for rotation inopposite directions by a constantly rotated driving element. The lattertakes the form of a pulley 16 (Fig. 4) driven by a belt 11 from asuitable source of power such as an electric motor 18 on the carriage. Agear 19 rotatable with the pulley meshes with two gears and 8| fast onshafts 82 and 83 carrying worms 84 and 85 disposed on diametricallyopposite sides of the member 50 and adapted to mesh with teeth v86 cutaround the periphery of the member so as to form the clutches l 04 andI05.

The pulley shaft and the shafts 82 and 83 are journaled in bearings in abar 81, and the shafts are supported for lateral movement by upstandingarms 88 and 89 loose on the shafts adjacent the bar and pivoted at theirlower ends on a plate 90 secured to the carriage. The bar 8'! is thussupported for horizontal movement in opposite relay I I1.

directions to carry one or the other of the worms 84 and 85 into and outof mesh with the worm wheel 50 and thereby actuate the two clutchesalternately. Such shifting of the worms is efiected by selectiveenergization of two electromagnets 9| and 92 having poles 93 and 94disposed on opposite sides of an upstanding armature 95 fast on one endof a rockshaft 96. The latter is journaled in the plate 90 and has thearm 88 fast on its opposite end. As a result, energization of the magnet9| will attract the armature and rock the shaft 96 in a direction toshift the worm 84 into mesh with the wheel 50 causing the latter to turncounter-clockwise. When the magnet 92 is energized, the worm 34 isdisengaged and the worm 85 shifted into mesh, the member 50 being thendriven clockwise. Non-magnetic spring clips 91 on the magnet poles limitthe movement of the armature and prevent freezing of the latter againstthe poles.

The light sensitive device 5 is preferably of the selenium cell typemounted within a holder I00. Herein, the holder is rigid with the outerend of a tube IOI projecting rigidly from the forward end of thecarriage 9 beneath the glass panel 6. The effective light sensitive areaof the cell 5 is larger than the circle I in which the beam 3 tends tooscillate so that the cell is operative in all of the differentpositions of the beam.

When the light beam 3 is intercepted by the pattern line 2, theresistance of the photosensitive cell is increased and the current isaccordingly decreased. To detect with a high degree of accuracy therises and falls of the cell current relative to a predeterminedadjustable value, one terminal of the cell is grounded and the otherterminal is connected by conductor I01 (Fig. 28) to the control grid I08of a so-called pentode type thermionic tube I09 which may be a type 6J7tube. The cathode heater IIO of this tube is heated by current derivedfrom a secondary III of the multiple voltage transformer I03. Through afull wave rectifying system indicated generally at II2, the propervoltage is impressed upon the plate II3 of the tube I09. The propernormal grid bias of the tube for different pattern densities is obtainedby selective adjustment of rheostats H4 and H5.

When the beam 3 is not intercepted, maximum current will flow throughthe cell 5. This current, flowing through rheostats II4-I I5, makes morepositive the potential impressed upon the grid I08, so that the tube I09is rendered conductive. The output or plate current from the tube I09flows through a resistor II3 thus making more negative the potential oncontrol grids I23 of an amplifier tube H6 so that the output platecurrent of the latter is decreased. The plate circuit of this lattertube is arranged to energize a This tube has been shown as a twin triodeand may be a type 53 tube. When the output of the tube H6 is minimum,the coil III will be deenergized and the spring II9 closes the switchI2I. In response to interception of part of the light beam 3 by thepattern line, the resistance of the cell 5 increases resulting in acorresponding decrease in the plate current of the tube I09, and anincrease in the tube H6 and the current energizing the relay H1. Thecoil II'I attracts the armature II8 against the pull of the spring IISand closes the switch I20.

Selective closure of the switches I20 and I2I is utilized through themedium of a twin triode tube I22 to effect energization of the clutchcontrol magnets 9| and 92. For this purpose, the cathode heater I25 ofthe tube I22 is energized from the secondary I24 and the plates I26 andI21 of the tube are connected to the magnets 92 and 9|. The arrangementis such that when the switch l2I is closed current will flow throughresistor I2I', thereby-increasing the potential in grid I26 and currentflow from the plate I26, which produces effective energization of themagnet 92. Similarly, when the switch I20 is closed, current will flowthrough resistor I20 increasing the potential of the grid I21 so currentflows from plate I21 and the magnet 9I is energized.

As a result of the circuit arrangement above described, the magnet 92will be energized, the worm and therefore the clutch I04 engaged, andthe valve control member 50 rotated in a clockwise direction in responseto a continuous full-light condition, that is, when all or apredetermined major portion of the light beam area is exposed to thetransparent medium 4. When all or more than said predetermined portionof the light beam area is intercepted by the pattern line 2, which willhereinafter be referred to as the no-light condition, the magnet 9I willbe energized and the worm 64 shifted to engage the clutch I05 and turnthe valve control member 50 continuously in a counter-clockwisedirection. The dividing line between the no-light and fulllightconditions, that is the portion of the light beam which must beintercepted by the pattern line to change from full-light to no-lightcondition may be varied widely by adjustment of the rheostats H4 and H5to change the normal grid potential of the tube I09.

By utilizing the switches of the relay II'I through the medium of-theduplex tube I22 instead of directly to control the energization of themagnets 9I and 92, the current burden on the switches is reduced to anextremely low value. This enables the movement of the armature II8 to bereduced to a value, on the order of two thousandths of an inch, withoutany attendant sparking at or burning of the contact surfaces. Thesensitivity of the photoelectric system, that is, its ability to respondto small changes in light intensity and reverse the energization of themagnets 9| and 92, is increased accordingly.

Operation The manner in which a pattern is traced and its outlinereproduced by operation of the cutter on the work will be explained withreference to Figs. 16 and 24 to 27. Let it be assumed that thephotoelectric cell is associated with the clutch magnets so as to engagethe clutch I04 and produce clockwise turning of the valve control member50 and the light beam in response to detection of a full-lightcondition, that is, when the beam is not intercepted by the pattern.Rotation of the member 50 continuously under such a condition willresult in oscillation of the Valve arms 41 and 41 back and forth betweentheir extreme positions so that the mean position of each valve arm isits neutral position. This oscillation is so rapid due to the highsensitivity of the electric system and the valve operating and cutteractuating mechanisms are so sluggish due to inertia of the parts,yielding of the hydraulic connections, etc. that no appreciable movementof the carriage 9 and cutter actually takes place. Conversely,iniresponse to a no-light condition, that is, when the beam 3 ispartially intercepted by the pattern and the condition of the magnetsand clutches is reversed, the member 60 will turn counter-clockwise andthe valve rotorswill be oscillated constantly. However, since theadmission .of fluid to one end of each cylinder is of the same shortduration as that during which fluid is admitted to the other end, thecarriage remains substantially stationary.

If, as will usually be the case in flame cutting, the pattern is to bereproduced accurately, that is, the cutting flame directed from thetorch I is to describe a path of exactly the same size as the pattern,the eccentric pin 66 will, by adjustment of the collar 61 about theshaft I as permitted by the set screw 68, be adjusted so that when thevalve control member 50 is in its east position (Fig. 24), the lightbeam 3 will lie on a line extending through the axes of revolution ofthe beam and the member.

Now assume that the machine has been placed in operation with the traceror light beam operatively associated with a line extending in a true inand out movements will be exactly in proportion to the change in thecontour of the then northerly direction. In such a case, the light beamwould oscillate inwardly across the outer margin of the line asindicated at I (Fig. 2'7) and then outwardly along a path I3I whilesimultaneously being advanced along the line 2 in the north direction bymovement of the saddle I0 along the bed ways. During the movement of thebeam along the path I30, the magnet 92 is energized and the valvecontrol member 50, turning in the same clockwise direction, shifts thevalve 3| toward the east position, the rotor of the valve 32 remainingsubstantially stationary because the eccentric 52 is on dead center withrespect to this valve. As soon as a sufiicient area of the beam has beenintercepted to produce the no-light condition, this depending on thecircuit adjustments, the magnet 92 is deenergized and the magnet 9! isenergized, the clutch I05 becoming effective to reverse the rotation ofthe member 50 and the light beam. The beam then traverses the path i3Iunder the no-light condition, and the motions of the valve arms 47 and Mare similarly reversed. So long as the pattern margin continues in thenorth direction, the opposite oscillations will be of equal length andthe mean position of the light beam will fall on the pattern outline.Also, while the member 50 and the valves actuated thereby are similarlyoscillated back and forth across the true northerly position, themovements in Opposite directions beyond such position are of equallengths with the result that the mean effective flow of fluid is to therod end of the cylinder I6 onlv which causes the saddle It] to movenorthward.

As previously pointed out, the oscillations of the valve control member50 are of short amplitude (on the order of a few thousandths of an inch)and the period of each oscillation (about a sixth of a second) due tothe extreme sensitivity of the photoelectric cell and the associatedcircuits is somewhat less than the interval required for the clutches,the valves and the hydraulic actuators to respond to a change in theposition of the tracer. As a result, the only fluid flow which iseffective is to the rod end of the cylinder I6 which causes truenortherly movement of the saddle I 0 and therof ore of the cutter 8 andthe tracer mounting.

When the tracer encounters the portion of the pattern which curveseastward, as it will during the outward movement I33, less movement isrcquired to reach the full-light condition. For the same reason, theinward movements I34 required to detect the no-light condition will begreater.

The changes in the amplitudes of the I active portion of the pattern,the result being to correspondingly change the mean position of thevalve control member 50 progressively toward the east. Fluid is thusadmitted to the head end of the cylinder I5 and simultaneously the flowto the cylinder I6 is reduced, the relative rates of flow being meteredto correspond to changes in the pattern contour.

As an incident to these changes in the mean position of the valvecontrol member 50, the direction of arcuate oscillation of the tracerwill be correspondingly changed by virtue of actuation of the tracermounting from the shaft 5| through the medium of the eccentric. Theresult is that the angles a: at which the light beam crosses the patternduring its inward movements remain substantially constant. The same istrue of the angles which the beam paths make with the path in movingoutwardly. That is to say, the range of oscillation of the light beamshifts automatically around the circle III as the pattern contourchanges so that there is a substantially constant angular relationshipbetween the inward and outward movements of the tracer and a tangent tothe portion of the pattern which is in active control of the light. Bythus changing the direction of oscillation of the tracer relative to thepattern automatically to conform to changes in the pattern contour, itis possible to follow completely around the periphery of any pattern,that is, do so-called peri-cutting, Without the necessity of changingquadrants or making other manual adjustments.

By the time the tracer reaches the northeasterly extending portion I35of the pattern, the parts will be positioned as shown diagrammaticallyin 1'7. Then, fluid will flow at equal rates into the rod and head endsrespectively of the cylinders I6 and I5 producing a resultant northeastmovement of the carriage 9. When the tracer encounters the eastwardlyextending portion I36 of the pattern, the member 50 and the valves willhave been shifted to the east position, there being no effective fluidflow to the cylinder I6. Thus, due to the straightness of the patternline, the amplitudes of the in and out oscillations l3! and I38 becomeuniform, thereby maintaining the true east mean position of the valvecontrol member '50 (Fig. 18).

Fig. 27 also illustrates on an exaggerated scale the manner in which thetracer functions to de-- tect a very sharp change in curvature of thepattern. In the case, for. example, of a sharp right angular corner I39,the beam 3 will, following an outward movement H0, berequired to movethrough a substantial angle along a path MI before encountering thepattern to produce the next no-light condition. This results in turningof the member 50 through an equally large angle producing a suflicientshift in the valve positions to cut off the supply of fluid to thecylinder- I5 and permit the full flow to the head end of the cylinderI6. The'direction of advance of the carriage is thus changed suddenlyfrom a substantially eastward to a southward direction. Thereupon, thetracer oscillations become uniform and the cutter continues southward inaccordance with the pattern outline.

The action above described takes place automatically in changing themotion of the controlled object to other quadrants. Thu as the patternline being traced changes from a south to a southwestward direction, thedirection of oscillation of the tracer shifts as shown in Fig. 21, thevalve arms 41 and 41' being moved into the south and west segments. Thecondition of the valves as the direction of oscillation of the lightbeam to advance the cutter toward the west and northwest respectivelyare shown in Figs. 22 and 23. It will be apparent therefore that thelight beam will follow automatically around the entire periphery of apattern line,

causing the controlled object to reproduce thepattern on the work withextreme accuracy. When the control described is governed by a pattern ofthe relatively complicated shape shown in Fig. 2, the cutter willtraverse a path which does not depart more than .004 of an inch from thecontrolling pattern outline. In fact, the control is so sensitive andaccurate that the light beam will follow along both sides and around theends of a single narrow ink line.

It will be apparent that with the method above described, the tracer andthe pattern are moved relative to each other longitudinally of thepattern outline and at the same time are continuously moved relat've toeach other transversely of the pattern outline to alternately increaseand decrease the interception of the contour by the tracer and to varythe amounts of the increases and decreases in accordance with changes inthe direction of the pattern outline. These changes are averaged andutilized to vary the direction of the first-mentioned longitudinalmovement so that the latter motion is of stepless character and areproduction of the pattern outline. The transverse relative movements,it will be observed, occur continuously at frequently repeated intervalsduring which the alternate interception and clearing of the pattern bythe tracer occurs at successive points closely spaced progressivelyalong the pattern, each tracer relative to its mounting being alone apredetermined orbital path the tracer mounting.

When the pattern a transparent medium, either side of the line may betraced. In such a case, the light beam moves in opposite directions whentracing the inner and outer sides of the line. This is for the reasonthat the light beam must move in different directions transversely ofthe line to detect-either the nolight or the full-light condition. Thesame effeet will result from reversing the connections to the magnets 9|and 92.

Sometimes it is desirable to cut the work piece larger, by a fixedincrement than the controlling pattern, This would be done, for example,in flame cutting where the work piece is to be further machined toproduce a final peripheral contour equal to that of the pattern. Or,when the controlled object is a cylindrical milling cutter, as indicatedat I43, Figs. and 26, it is necessary to compensate for the radius ofthe cutter in order to reproduce the pattern contour. Both of these endsmay be attained by ofisetting the center of the light beam 3 laterallyfrom a line I44 through the axis 10' of oscillation of the beam 3 andthe control member when the latter member is in the extreme eastposition. To do this, the member 50 is first located in the eastposition, and then after loosening the set screw 68, the collar 61 isturned relative to the shaft 5| until the beam 3 is offset from the lineI44 a distance I45 equal to the radius of th milling cutter I43. Formilling cutters of larger size such a is illustrated in Fig. 26, it maybe necessary,

transverse motion of the a which is fixed relative to is in the form ofa line on in order to obtain the necessary offset I46, to re-,

move the collar 61 and replace it by one having an eccentric pin 66adapted to produce a greater radius of oscillation of the light beam.

In milling profiles the foregoing method of compensation for the cutterdiameter is particularly advantageous in that it simplifies the makingof the pattern. The latter may be of the same size as the work contourto be produced.

It is of course desirable, for the sake of obtaining optimum accuracy ofpattern reproduc tion, that the orbit in which the light beam oscillatesbe as small as practicable. With the form of the invention firstdescribed, the circle 10 is about .060 of an inch in diameter. In anycase, however, the eifective control area of the photoelectric cell issufficiently large to respond to the light intensity in all position ofthe beam around its orbital path.

While it is preferred that the tracer element be a light beam, becauseof the simplicity of the pattern that may be employed and because of theprecision obtainable in reproduction, other types of tracers andpatterns may be used. For example, the pattern may be a solid ofconducting material and the tracer a piece of resilient wire projectingaxially from the casing I or equivalent mounting. In such a case, thewire would constitute a laterally yieldable contact coacting with thepattern to form a switch by which one of the magnets 9| or 92 would beenergized, the magnet armature being spring urged in the oppositedirection. Or, the pattern may be made of non-conducting materialoperating in conjunction with a yieldable tracer arm carrying bothcontacts of the control switch which is closed and opened in response toengagement of the tracer arm with or disengagement of the arm from thepattern surface.

I claim as my invention:

1. The method of governing the relative movements between two objects inaccordance with the outline of a pattern, said method comprisingdirecting a beam of light toward the pattern, moving one of said objectsand the light beam in unison relative to the other object to advance thebeam along the pattern outline while continuously and irrespective ofthe pattern outline oscillatingthe beam transversely of the patternoutline and relative to said one object to alternately and invariablyincrease and decrease the interception of the beam by said pattern, andchanging the direction of relative advance between said objects inaccordance with average changes in the lengths of the light increasesand decreases.

2. The method of positioning a controlled object in conformance to apattern contour which comprises directing a beam of light toward'saidpattern, effecting relative movement between said beam and the patternto cause the beam to follow along the pattern contour, simultaneouslyand continuously moving said beam alternately back and forth across thepattern outline irrespective of the contour of the latter to increaseand decrease the interception of the beam by the outline and vary theamounts of the increases and decreases in accordance with changes in theshape of the outline, and controlling the relative positioning of saidcontrolled object in any one or a combination of four rectangulardirections selectively in accordance with the mean effective position ofsaid light beam.

3. The method of controlling the relative movements of a controlledobject in accordance with a pattern contour which comprises continuouslyoscillating a control element back and forth in opposite directionstransversely of the pattern outline and along different arcuate portionsof a complete orbital path which is fixed relative to said object,changing the portions of said path traversed by said control element inaccordance with changes in the pattern contour to maintain a generallyconstant angular relationship between the pattern contour and the pathof oscillation of said element, relatively moving said controlled objectand simultaneously relatively moving said element and the pattern alongthe path defined by the mean position of the said element in itssuccessive transverse oscillations whereby to cause said element tofollow around the entire perimeter of a pattern.

4. The method of controlling the relative movements between two objectsto describe a pattern outline which comprises continuously moving atracer back and forth repeatedly at substantially regular intervals andin a predetermined orbital path alternately into and out of contact withthe peripheral outline of a pattern irrespective of the contour of thelatter whereby to shift the range of interception of said patterncontour along said path with changes in the pattern contour, and varyingthe direction of relative movement between said objects in accordancewith the changes in the increases and decreases of pattern interception.

5. The method of governing the relative movements of a controlled objectto reproduce a pattern outline, said method comprising relatively movingsaid controlled object and a light beam in unison to advance the latteralong the pattern outline, continuously oscillating the beam back andforth along arcuate paths of predetermined curvature and extendinglaterally toward and away from said outline, varying the directions andamplitudes of successive oscillations in accordance with changes in thepattern outline, and changing the direction of relative advance of saidobject and beam to correspond to changes in the mean position of saidbeam.

6. The method of relatively positioning a controlled object inconformance with a pattern contour which comprises efiecting relativemove ment between a pattern element and a tracer element to cause oneelement to follow the pattern contour while simultaneously andcontinuously moving the elements intermittently toward and away fromeach other transversely of said contour and irrespective of the shape ofthe latter to shift the tracer element relative to said controlledobject alternately onto and off from said contour, and controlling therelative movement of said controlled object in any one or a combinationof four rectangular directions selectively in accordance with the meanpath traversed by the movable element.

'7. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a pattern outline having, incombination, a control member, hydraulic actuating means for relativelymoving said objects in any planar direction, valve means positioned inaccordance with changes in the position of said member and controllingsaid hydraulic means to cause relative movement of the objects in adirection determined by the instantaneous posl-' tion of said member, aphotosensitive cell, a light beam directed toward said cell andoscillated back and forth along diflerent parts of a completepredetermined orbital path, said beam being movable in unison with saidmember, a pattern coacting with said tracer to determine the extent ofeach oscillatory motion thereof, an electrical system having twowindings energized selectively in accordance with changes in the lightintensity on said cell, and reversible driving means for said membercontrolled by said windings, the frequency of oscillation of said beamand the inertia of said actuating means being sufliciently high thatsaid controlled object is not responsive to the individual oscillationsof said light beam.

8. A machine for causing relative movement between two objects toreproduce a pattern contour having, in combination, a pattern, a tracerincluding a light beam directed toward the outline of said pattern, amounting movable in unison with one of said objects and supporting saidtracer for movement of said beam in an orbital path relative to saidpattern, a photosensitive cell on the opposite side of said patternhaving an efiective control area greater than the orbit described by thelight beam in moving completely around said path, means for oscillatingsaid tracer relative to said' mounting transversely of the patternoutline and for shifting the range of such oscillation along differentportions of said path automatically with changes in the pattern contour,and power actuated mechanism controlled by said cell and operating tocause one of said objects and said tracer mounting to move relative tothe other object and follow the changes in the mean position of saidtracer.

9. Mechanism for relatively moving a controlled object having, incombination, a transparent medium having contiguous relatively light anddark areas the junction of which defines a pattern outline, a tracerdevice for directing a beam of light through said medium, a lightsensitive device disposed on the opposite side of said medium forimpingement of the beam thereon. mechanism controlled by said lightsensitive device ior invariably causing intermittent relativeoscillation of said devices in a zigzag path around the pattern outlineincluding straight portions of the latter, and power actuated meanscontrolled by said mechanism for causing said controlled object totraverse the mean path described by the oscillated device.

l0. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a a pattern outline having, incombination, an hydraulic actuator for relatively moving said objects,means controlling said actuator selectively to cause relative movementof said objects in different directions including two windings, and anelectrical system controlling the selective energization of saidwindings in cluding a tracer supported by one of said objects andcontinuously oscillated back and forth transversely of the patternoutline and relative to its supporting object, the period of oscillationof said tracer being less than the response of said actuator to changesin the energization of said windings whereby no relative movement occursin response to the individual oscillations of said tracer but followsonly the changes in the mean position thereof.

11. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a pattern outline having, incombination, a rotary control member, hydraulically actuated meansoperating continuously to relatively move said objects in a directioncorresponding to the instantaneous position of said member, valve meanspositioned selectively in accordance with the angular position of saidmember to meter the flow of pressure fluid to said hydraulicallyactuated means and cause said relative movement in any one or anycombination of four rectangular directions, a tracer movable in unisonwith the rotary motion of said member, a pattern having a peripheraloutline interposed in the path of said tracer, reversible electric motordriving means for said member having two windings selectivelyenergizable to cause turning of the member in opposite directions, andmeans responsive to movements of said tracer in oppositie directionsinto and out of contact with the outline of said pattern to control thealternate energization of said windings.

12. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a pattern outline having, incombination, a rotary control member, hydraulic actuating means torelatively move said objects in any planar direction, valve meansactuated by said member and controlling said actuating means to causesaid relative movement in accordance with the instantaneous angularposition of said member, a pattern, a tracer movable in unison with therotary motion of said member in an orbital path extending transverselyof the peripheral outline of said pattern, and means controlled by saidtracer'to cause said member to turn alternately in opposite directionsin response to movement of said tracer into and out of contact with saidpattern ouline.

13. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a pattern outline having, incombination, a rotary control member, power actuated means operatingcontinuously'to relatively move said objects in any direction determinedby the instantaneous angular position of said member, a pattern, atracer movable in unison with the rotary motion of said member in anorbital path extending transversely of the peripheral outline of saidpattern, and means con trolled by said tracer to cause said member to iturn alternately in opposite directions in response to movement of saidtracer into and out of contact with said pattern outline.

14. Mechanism for, relatively positioning a controlled object inconformance to a pattern contour having, in combination, a patternelement, a tracer element, means for efiecting relative movement betweensaid elements to cause one element to follow completely around thepattern contour, means supporting one of said elements for independentmovement transversely of the pattern contour and relative to saidcontrolled object, means operating continuously to move the movableelement relative to its support to alternately increase and decrease theinterception of the contour by the tracer element and vary the amountsof the increases and decreases as the contour changes, and poweractuated means responsive to said transverse movements and operable torelatively move said controlled object in any one or a combination offour rectangular directions selectively in accordance with the mean pathtraversed by the movable element.

15. Mechanism for controlling the relative movements of a controlledobject in accordance with a p'attem contour having, in combination, acontrol element mounted for oscillation relative to said controlledobject transversely of the pattern outline, means for oscillating saidelement continuously, means controlled by said element for changing theangle of its oscillation in accordance with changes in the patterncontour to maintain a generally constant angular relationship betweenthe path of oscillation and the effective portion of the pattern, andpower actuated mechanism controlled by said element and operating torelatively move said controlled object and simultaneously to relativelymove said element and the pattern along the path defined by the meanposition of the said element in its successive oscillations whereby tocause said element to follow around the entire perimeter of a pattern. I

16. Mechanism for causing one object to move relative to another objectand traverse a path corresponding to a pattern outline having, incombination, a control member, power actuated means for moving saidobject in any planar direction, means positioned in accordance withchanges'in the position of said member and controlling said poweractuated means to cause relative movement between said objects in adirection determined by the instantaneous position of said member, atracer oscillated back and forth. along different parts of a completepredetermined orbital path and movable in unison with said member, apattern coacting with said tracer to determine the extent of eachoscillatory motion thereof, and means for positioning said member inaccordance with the mean position of said tracer.

1'7. A machine for causing relative movement of a controlled object toreproduce a pattern contour having, in combination, a tracer, a mountingmovable in unison with said controlled object and supporting said tracerfor movement independently of the controlled object in a predeterminedcircular path relative to said pattern, means for oscillating saidtracer relative to its mounting back and forth relative to the patternoutline, power actuated mechanism to relatively advance said object andsaid tracer mounting in accordance with changes in the mean position ofsaid tracer, and means for varying the angle of the tracer oscillationsin conformance with changes in the pattern contour.

18. Mechanism for causing relative movement of a controlled objectcorresponding to a pattern outline having, in combination, a rotarycontrol member, power actuated means for operating automatically torelatively move said object in any direction determined by theinstantaneous angular position of said member, an eccentric rotatablewith said member, a pattern, a tracer therefor moved in an orbital pathby said eccentric, and means controlled by said tracer to cause saidmember to turn in opposite directions when said tracer is disposed onopposite sides of said pattern outline.

19. In a tracer control of the character described, a source of light,means receiving rays of light from said source and converging the sameto form a beam constituting a pattern tracer, and means supporting saidlast mentioned means for movement in an orbital path independently ofsaid light source whereby to minimize-the weight of the parts requiredto be moved to oscillate said beam in said path.

20. A machine for efiecting relative movement between two objects toreproduce a pattern contour having, in combination, a tracer, meanssupporting said tracer on one of said objects and for independentoscillatory movement relative to its support transversely of a patternoutline and at variable angles, means for continuously moving saidtracer relative to its mounting back and forth transversely of thepattern outline and irrespective of the contour of the latter whilemaintaining asubstantially constant angle between such movements and thepattern outline, and power actuated mechanism to advance said one objectand the tracer mounting relative to the other object and in accordancewith changes in the mean position of the tracer.

21. The method of controlling the tracing of a contour which comprisesrelatively moving said contour and a tracer longitudinally of the contour, and during such relative movement continuously imparting otherrelative movement between said tracer and said contour transversely ofthe contour to alternately increase and decrease the interception of thecontour by the tracer and to vary the amounts of the increases anddecreases in accordance with changes in the direction of the contour,and varying the direction of said first mentioned relative movement inaccordance with the changes in the amounts of the increases anddecreases.

22. The method of controlling the tracing of a contour which comprisesrelatively moving said contour and a tracer longitudinally of thecontour, and during such relative movement continuously imparting otherrelative movement between said tracer and said contour transversely ofthe contour along a predetermined orbital path to alternately increaseand decrease the interception of the contour by the tracer with changesin the direction of the contour, and varying the direction of said firstmentioned relative movement in accordance with changes in the increasesand decreases in interception of the contour.

23. The method of controlling the tracing of a contour which comprisesrelatively moving said contour and a tracer longitudinally of thecontour, and during such relative movement continuously imparting otherrelative movement between said tracer and said contour transversely ofthe contour to alternately increase and decrease the interception of thecontour by the tracer at successive points closely spaced progressivelyalong the contour and to vary the amounts of the increases and decreasesin accordance with changes in direction of the contour, and varying thedirection of said first mentioned relative movement in accordance withchanges in the amounts of the increases and decreases of interceptiondue to changes in the contour.

24. The method of controlling tracing of a contour which comprisesrelatively moving said contour and a light beam longitudinally of thecontour, and during such relative movement, continuously moving saidbeam and contour relative to each other transversely of the contour toalternately increase and decrease the interception of the beam by saidcontour and to vary the amounts of the increases and decreases inaccordance with changes in the direction of the contour, and varying thedirection of said first mentioned relative movement in accordance withthe changes in the amounts of the increases and decreases in lightinterception.

25. Mechanism for governing the relative movements between work and toolsupports to reproduce a pattern outline comprising, in combination,power actuated means for effecting relative movement between saidsupports in any direction in a plane, one of said supports providing amounting for said pattern, means on the other of said supports adaptedto rotate in a circle which is fixed relative to the latter support andto direct a beam of light toward said pattern, power actuated mechanismfor relatively moving said beam and pattern along said circle toalternately intercept and clear the pattern, a photosensitive devicefixed on said other support and responsive to the varying amounts ofpattern interception by said light beam, and means controlled by saiddevice and governing the direction of relative advance of said supportsby said power actuated means to reproduce the pattern outline and causerelative motion between said beam and pattern longitudinally of thelatter.

26. In a mechanism for controlling the repro- -duction of a contour, thecombination of, a

tracer, power actuated means for moving said tracer and contour relativeto each other along the contour, power actuated means operablecontinuously to move said tracer and contour relative to each othertransversely of said first mentioned relative movement and alternatelyonto and off from the contour to increase and decrease the interceptionand vary the amounts of the increases and decreases as the contourchanges, and means for varying the direction of said first mentionedrelative movement in accordance with variations in the interception ofsaid contour by said tracer.

2'7. In a mechanism for controlling the reproduction of a contour, thecombination of, a tracer comprising a beam of light projected towardsaid contour, means for relatively moving said contour and light beamalong the contour, means operable during such relative movement forcontinuously imparting other relative movement between said tracer andcontour transversely of the contour to alternately increase and decreasethe interception of the light beam by the contour and vary the amountsof the increases and decreases as the contour changes, and mechanismincluding a light sensitive device responsive to the varying amounts oflight interception by said contour and operable to vary the direction ofsaid first mentioned relative movement and thereby follow changes in thedirection of said contour.

28. In a mechanism for controlling the reproduction of a contour, thecombination of a tracer, a tool, and a workpiece, means for moving saidtracer and contour relative to each other along the contour, meansoperable continuously to move said tracer and contour relative to eachother transversely of said first mentioned relative movement andalternately onto and off from the contour to increase and decrease theinterception and vary the amounts of the increases and decreases as thecontour changes, means for varying the direction of said first mentionedrelative movement in accordance with variations in the interception ofsaid contour by the tracer, means controlled by both of said relativemovements for relatively moving said tool and workpiece in a path toreproduce said contour, and means for adjusting said mechanism to varythe range of said path relative to the size of said contour.

ARTHUR A. MEYER.

